Antimony-containing composite oxide catalysts are widely known as catalysts for the production of aldehydes and unsaturated acids by oxidation reactions of organic compounds, and the production of nitriles and hydrocyanic acid by ammoxidation reactions. Antimony-containing composite oxide catalysts are particularly useful for ammoxidation reactions, and are used, for example, in the production of acrylonitrile by ammoxidation of propylene, and in the production of hydrocyanic acid by ammoxidation of methanol.
Numerous investigations have already been conducted into catalysts for use in oxidation reactions and ammoxidation reactions, and a great variety of catalysts have been proposed.
For example, Patent Document 1 discloses a composite oxide catalyst of antimony and at least one element selected from the group consisting of iron, cobalt and nickel.
Investigations into improving these catalysts are also being actively pursued, and for example, Patent Documents 2 to 11 discloses catalysts in which tellurium, vanadium, tungsten, molybdenum or phosphorus or the like is added to the iron and antimony.
Moreover, investigations continue to be conducted into improving the yield of the target product by improving the catalyst preparation process. For example, Patent Documents 12 to 16 disclose a process for adjusting the pH of a slurry containing antimony and polyvalent metal compound, and a process for heat-treating a slurry and the like.